The microscopy core facility has been assembled under the leadership of a microscopist and cell biologist of long-standing to ensure that coverage of the diverse microscopy needs of the three projects are adequately maintained throughout the three years of this grant proposal and to direct the duties of the microscopist hired for this project. Microscopic techniques will be used to: 1) evaluate the integrity of the diaphragm of SCID mice injected with the various cell lines (Projects 2 & 3) using scanning electron microscopy; 2) determine basement membrane invasion of SCID mouse organs and tissues by the different prostate cell lines using transmission electron microscopy; 3) localize the expression of specific integrins during tissue invasion in SCID mouse using immunogold probes at the TEM level (Projects 2 & 3); 4) perform 3-D reconstruction of the distribution of integrins and collagenase enzymes and TIMPs localized by specific antibodies by indirect immunofluorescence (Projects 2 & 3). These studies will be performed on prostate tumors of different grades and degree of invasiveness using confocal microscopy (Project 1).